1. Field of the Invention
Embodiments of the present invention generally relate to methods for depositing silicon dioxide by atomic layer deposition (ALD).
2. Description of the Related Art
In the field of semiconductor processing, flat-panel display processing or other electronic device processing, vapor deposition processes have played an important role in depositing materials onto substrates. As the geometries of electronic devices continue to shrink and the density of devices continues to increase, the size and aspect ratio of the features are becoming more aggressive. Accordingly, conformal deposition of materials to form these devices is becoming increasingly important.
While conventional chemical vapor deposition (CVD) has proved successful for device geometries and aspect ratios down to about 0.15 μm, the more aggressive device geometries require an alternative deposition technique. One technique that is receiving considerable attention is ALD. During an ALD process, reactant gases are sequentially introduced into a process chamber containing a substrate. Generally, a first reactant is pulsed into the process chamber and is adsorbed onto the substrate surface. A second reactant is then pulsed into the process chamber and reacts with the first reactant to form a deposited material. A purge step may be carried out between the delivery of each reactant gas. The purge step may be a continuous purge with a carrier gas or a pulse purge between the delivery of the reactant gases.
The formation of silicon dioxide by ALD is a process that is known in the art. In forming silicon dioxide by ALD, a silicon precursor may be pulsed into the chamber followed by an oxidizing source. When water is used as the oxidizing source, the ALD process typically requires a high temperature and a longer exposure time due to the moderate reactivity of water.
Therefore, there is a need in the art for a method and apparatus for depositing silicon dioxide using water in an ALD at a low temperature.